The present invention relates generally to a grain dryer, and more particularly to an apparatus and method for metering grain in a grain dryer.
In many instances, agricultural grain products must be stored for an extended period of time prior to being used. However, prior to storage, it is necessary to dry the grain to a condition in which it is less subject to molding or other deterioration. Accordingly, it has become known to remove moisture from grain by passing the grain through a grain dryer prior to storage.
Grain dryers typically have a plenum chamber through which heated air is advanced. The grain is passed through columns which surround the plenum chamber. Each column includes an inner perforated wall that is in fluid communication with the plenum chamber and an outer perforated wall which is in fluid communication with the ambient environment surrounding the grain dryer. As the grain moves through the column, heated air from the plenum chamber passes through the inner perforated wall, through the flow of grain, and out through the outer perforated wall. As the heated air moves through the flow of grain, moisture is removed from the grain.
To control the amount of moisture removed from the grain, it is necessary to precisely control the flow rate of the grain through the grain column. In particular, grain that remains in the grain column and is exposed to the heated air for an extended period of time may become too dry and even catch on fire, whereas grain that passes quickly through the grain column may retain an undesirable amount of moisture. To control the flow rate of grain through the grain column, a metering roll is utilized at a discharge opening of the grain column. In particular, the metering roll is located in a relatively narrow grain flow metering passage, and rotation of the metering roll within the metering passage causes grain to be advanced through the grain column at a desired rate. Controlling the speed of rotation of the metering roll controls the flow rate of grain through the grain dryer which, in turn, controls the amount of moisture removed from the grain.
A problem with grain dryers that have heretofore been designed is that trash objects can accumulate at or near the metering roll within the metering passage. In particular, high volume grain harvesting techniques now used cause a variety of trash objects to become intermixed with the grain as the grain is harvested. Typically, the trash objects include stalks, corn cobs, and other non-grain material. Because the flow of grain through the grain column is controlled by rotation of the metering roll within the metering passage, the trash objects tend to accumulate at or near the metering roll within the metering passage. The trash objects that accumulate at or near the metering roll in the metering passage tend to disturb the proper flow of grain through the grain column thereby resulting in an improper amount of moisture being removed from the grain. In extreme cases, the trash objects may substantially block the flow of grain through the relatively narrow grain flow metering passage. This, in turn, may cause blockage of the flow of grain through the grain column, thereby causing the grain to be susceptible to catching on fire due to the grain being exposed to the heated air from the plenum chamber for an extended period of time.
What is needed therefore is an apparatus and method for accurately metering grain in a grain dryer which overcomes one or more of the above-mentioned disadvantages.